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Contact irritant responses of Aedes aegypti Using sublethal concentration and focal application of pyrethroid chemicals.

Manda H, Shah P, Polsomboon S, Chareonviriyaphap T, Castro-Llanos F, Morrison A, Burrus RG, Grieco JP, Achee NL - PLoS Negl Trop Dis (2013)

Bottom Line: Significant escape responses were also observed at <100% SAC using ½FAR of all test compounds.Results presented here suggest a potential role for sublethal and focal application of contact irritant chemicals in an Ae. aegypti push-pull strategy to reduce human-vector contact inside treated homes.However, the impact of an increase in escape response on dengue virus transmission is currently unknown and will depend on rate of biting on human hosts prior to house exiting.

View Article: PubMed Central - PubMed

Affiliation: Uniformed Services University of the Health Sciences, Department Preventive Medicine and Biometrics, Bethesda, Maryland, United States of America. hortancemanda@yahoo.fr

ABSTRACT

Background: Previous studies have demonstrated contact irritant and spatial repellent behaviors in Aedes aegypti following exposure to sublethal concentrations of chemicals. These sublethal actions are currently being evaluated in the development of a push-pull strategy for Ae. aegypti control. This study reports on mosquito escape responses after exposure to candidate chemicals for a contact irritant focused push-pull strategy using varying concentrations and focal application.

Methods: Contact irritancy (escape) behavior, knockdown and 24 hour mortality rates were quantified in populations of female Ae. aegypti under laboratory conditions and validated in the field (Thailand and Peru) using experimental huts. Evaluations were conducted using varying concentrations and treatment surface area coverage (SAC) of three pyrethroid insecticides: alphacypermethrin, lambacyhalothrin and deltamethrin.

Results: Under laboratory conditions, exposure of Ae. aegypti to alphacypermethrin using the standard field application rate (FAR) resulted in escape responses at 25% and 50% SAC that were comparable with escape responses at 100% SAC. Significant escape responses were also observed at <100% SAC using ½FAR of all test compounds. In most trials, KD and 24 hour mortality rates were higher in mosquitoes that did not escape than in those that escaped. In Thailand, field validation studies indicated an early time of exit (by four hours) and 40% increase in escape using ½FAR of alphacypermethrin at 75% SAC compared to a matched chemical-free control. In Peru, however, the maximum increase in Ae. aegypti escape from alphacypermethrin-treated huts was 11%.

Conclusions/significance: Results presented here suggest a potential role for sublethal and focal application of contact irritant chemicals in an Ae. aegypti push-pull strategy to reduce human-vector contact inside treated homes. However, the impact of an increase in escape response on dengue virus transmission is currently unknown and will depend on rate of biting on human hosts prior to house exiting.

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Related in: MedlinePlus

Experimental huts fitted with window and door interception traps.(A) Thailand, (B) Peru.
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pntd-0002074-g001: Experimental huts fitted with window and door interception traps.(A) Thailand, (B) Peru.

Mentions: Trials were conducted in both Thailand and Peru using experimental huts fitted with window and door interception traps. Three (Thailand) and five (Peru) portable huts were constructed using dimensions and materials that mimic indigenous homes at each site (Figure 1). Details of the experimental hut and intercept trap design in Thailand have been previously described [35]. In Peru, the huts measured 4 m wide×6 m long×6 m height. Each hut had two windows (96 cm wide×96 cm height) and two doors (1 m wide×2 m height); one window and one door each at the front and the back, which were fitted with interception traps. At both field sites, the huts were positioned on raised platforms 30 cm above ground. The support columns for the platform sit atop cement ant traps to prevent predation on indoor KD mosquitoes. Floors were covered with white plastic sheeting to facilitate the detection of KD responses. Huts at both locations contained metal frame panels with wire-mesh backing positioned along the interior walls. Treated fabric panels were fixed to these metal panels using magnets, thereby avoiding chemical contact with the wall surface and potential contamination during subsequent chemical testing or treatment concentration. Environmental parameters of indoor/outdoor temperature and relative humidity were recorded using HOBO data loggers (series H08-004-02 and H21-001, respectively). HOBO U30/NRC Data Logging Weather Stations (Onset Computer Corporation Cape Cod, MA, USA) were used at both sites and were positioned centrally to the experimental huts.


Contact irritant responses of Aedes aegypti Using sublethal concentration and focal application of pyrethroid chemicals.

Manda H, Shah P, Polsomboon S, Chareonviriyaphap T, Castro-Llanos F, Morrison A, Burrus RG, Grieco JP, Achee NL - PLoS Negl Trop Dis (2013)

Experimental huts fitted with window and door interception traps.(A) Thailand, (B) Peru.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585116&req=5

pntd-0002074-g001: Experimental huts fitted with window and door interception traps.(A) Thailand, (B) Peru.
Mentions: Trials were conducted in both Thailand and Peru using experimental huts fitted with window and door interception traps. Three (Thailand) and five (Peru) portable huts were constructed using dimensions and materials that mimic indigenous homes at each site (Figure 1). Details of the experimental hut and intercept trap design in Thailand have been previously described [35]. In Peru, the huts measured 4 m wide×6 m long×6 m height. Each hut had two windows (96 cm wide×96 cm height) and two doors (1 m wide×2 m height); one window and one door each at the front and the back, which were fitted with interception traps. At both field sites, the huts were positioned on raised platforms 30 cm above ground. The support columns for the platform sit atop cement ant traps to prevent predation on indoor KD mosquitoes. Floors were covered with white plastic sheeting to facilitate the detection of KD responses. Huts at both locations contained metal frame panels with wire-mesh backing positioned along the interior walls. Treated fabric panels were fixed to these metal panels using magnets, thereby avoiding chemical contact with the wall surface and potential contamination during subsequent chemical testing or treatment concentration. Environmental parameters of indoor/outdoor temperature and relative humidity were recorded using HOBO data loggers (series H08-004-02 and H21-001, respectively). HOBO U30/NRC Data Logging Weather Stations (Onset Computer Corporation Cape Cod, MA, USA) were used at both sites and were positioned centrally to the experimental huts.

Bottom Line: Significant escape responses were also observed at <100% SAC using ½FAR of all test compounds.Results presented here suggest a potential role for sublethal and focal application of contact irritant chemicals in an Ae. aegypti push-pull strategy to reduce human-vector contact inside treated homes.However, the impact of an increase in escape response on dengue virus transmission is currently unknown and will depend on rate of biting on human hosts prior to house exiting.

View Article: PubMed Central - PubMed

Affiliation: Uniformed Services University of the Health Sciences, Department Preventive Medicine and Biometrics, Bethesda, Maryland, United States of America. hortancemanda@yahoo.fr

ABSTRACT

Background: Previous studies have demonstrated contact irritant and spatial repellent behaviors in Aedes aegypti following exposure to sublethal concentrations of chemicals. These sublethal actions are currently being evaluated in the development of a push-pull strategy for Ae. aegypti control. This study reports on mosquito escape responses after exposure to candidate chemicals for a contact irritant focused push-pull strategy using varying concentrations and focal application.

Methods: Contact irritancy (escape) behavior, knockdown and 24 hour mortality rates were quantified in populations of female Ae. aegypti under laboratory conditions and validated in the field (Thailand and Peru) using experimental huts. Evaluations were conducted using varying concentrations and treatment surface area coverage (SAC) of three pyrethroid insecticides: alphacypermethrin, lambacyhalothrin and deltamethrin.

Results: Under laboratory conditions, exposure of Ae. aegypti to alphacypermethrin using the standard field application rate (FAR) resulted in escape responses at 25% and 50% SAC that were comparable with escape responses at 100% SAC. Significant escape responses were also observed at <100% SAC using ½FAR of all test compounds. In most trials, KD and 24 hour mortality rates were higher in mosquitoes that did not escape than in those that escaped. In Thailand, field validation studies indicated an early time of exit (by four hours) and 40% increase in escape using ½FAR of alphacypermethrin at 75% SAC compared to a matched chemical-free control. In Peru, however, the maximum increase in Ae. aegypti escape from alphacypermethrin-treated huts was 11%.

Conclusions/significance: Results presented here suggest a potential role for sublethal and focal application of contact irritant chemicals in an Ae. aegypti push-pull strategy to reduce human-vector contact inside treated homes. However, the impact of an increase in escape response on dengue virus transmission is currently unknown and will depend on rate of biting on human hosts prior to house exiting.

Show MeSH
Related in: MedlinePlus